El-nabulsi, R. A., & Rezazadeh, H. (2013). NON-STANDARD LAGRANGIANS WITH DIFFERENTIALS OPERATORS. Journal of Nonlinear Analysis and Optimization: Theory & Applications (JNAO), 5(2), 21–35. retrieved from https://ph03.tci-thaijo.org/index.php/jnao/article/view/2747